Drive device for movable structural component units

ABSTRACT

A drive device for movable structural component units, e.g. for a window lifter in motor vehicles, has a reversible electric motor and a control device for switching on the motor with predetermined rotating direction from its rotor shaft at a switch-on command. In order to manage with the lowest possible drive output and to keep the characteristic lines to be maintained by the motor within the narrowest possible range, both the motor and the structural component unit itself are constructed so as to be without friction and active self-locking is provided to keep the structural component unit in its movement end positions. For this purpose a sensor detects rotational movements of the rotor shaft from the movement end position and the control device is connected with an evaluating unit which evaluates the sensor signals and generates a switch-on command in a rotating direction opposite the rotational movement of the rotor shaft.

BACKGROUND OF THE INVENTION

The invention is based on a drive device for movable structuralcomponent units, particularly in vehicles, such as window lifters,sliding-roof actuators, mirror adjusters and the like.

More particularly, it relates to a drive device for movable structuralcomponent units, which has a reversible electric motor with a rotorshaft driveable in two rotating directions, and a control device forswitching on the motor in a predetermined rotating direction of therotor shaft at switch-on command.

An example of such a drive device for movable structural component unitsis an electric-motor window lifter in which the desired actuatingprocess of the side window panes of the vehicle can be triggered byactuating one of two selection switches for "window closing" and "windowopening". The triggered process of "window closing" or "window opening"runs automatically as long as the respective selection switch remainsactuated and is interrupted when the end position is reached by openingan end switch. The end switches have already been replaced in modernsystems by electronics with Hall sensors which switch off the drivemotor when the end position is reached or when there is an obstacle inthe window movement path (jamming protection).

To prevent the window pane from opening automatically, e.g. due toinherent weight or shaking, it is necessary for the drive device or thestructural component unit to be self-locking, which is brought about inpractice by great friction in the drive motor or in the window liftersystem. However, this has substantial disadvantages. On the one hand,the desired friction can be reproduced in the manufacturing process onlywithin a very great range of dispersion, so that the drive output of thedrive motor must be designed to be substantially greater than would benecessary in the isolated case in order to protect functioning. On theother hand, higher drive outputs require a correspondingly moreextensive layout of lines, fuse protection, battery capacity, etc.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to provide a drivedevice for movable structural component units, particularly in vehiclessuch as window lifters, sliding-roof actuators, mirror adjusters and thelike, which avoids the disadvantages of the prior art.

In keeping with these object and with others which will become apparenthereinafter, one feature of the present invention resides, brieflystated, in a drive device of the aforementioned type, which has a sensorfor detecting rotational of the rotor shaft assigned to the rotor shaftof the motor and effective at least in the switched-off state of themotor, and a control device containing an evaluating unit for evaluatingthe sensor signals and for generating a witch-on command in a rotatingdirection opposite the rotating direction of the rotor shaft.

When the drive device is designed in accordance with the presentinvention, it has the advantage that the drive device obtains aso-called active self-locking, i.e. monitors the movement end state ofthe driven structural component unit and switches on automatically whenthis movement end state is changed by external influences in order toreproduce the movement end state through corresponding drive force. Thismeans that both the drive motor and the structural component unit to bemoved can be constructed so as to have as little friction as possible.This likewise leads to a substantial savings in drive energy and enablesthe use of small drive motors with smaller connection outputs on theother hand. Low-friction systems can also be produced with asubstantially smaller fabrication spread than systems subject to a greatamount of friction, so that the characteristic lines to be maintained bythe drive motor for the movement flow of the structural component unitto be driven can be substantially limited.

In general the drive device according to the invention can monitor bothmovement end positions of the driven structural component unit and,depending on the movement direction of the structural component unitfrom the monitored end position, can start the drive motor in one drivedirection or the other as soon as the structural component unit has beenmoved out of the end position by external influences by more thantolerance value. In many cases of application, e.g. window lifters invehicles, it is only necessary to monitor one movement end position,e.g. the window closing position. In this case it is not necessary toknow the movement direction of the structural component unit and thecontrol electronics can be simplified.

At present, known drive devices for the side windows in vehicles arefrequently outfitted with so-called Hall integrated circuits,hereinafter Hall IC, which detect the revolutions of the rotor shaft ofthe drive motor. Corresponding control electronics then make it possibleto move directly to predetermined window positions, to switch off thedrive motor in the end positions of the window and to protect againstjamming, i.e. to switch off or reverse the drive motor in case of anobstacle in the window movement path. The drive device according to theinvention has the advantage that these Hall ICs can be used as sensorsfor determining the rotational movement of the rotor shaft, so that theadditional cost on electronics for the function of the activeself-locking according to the invention is quite low.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both as to its construction and its method ofoperation, together with additional objects and advantages thereof, willbe best understood from the following description of specificembodiments when read in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a block wiring diagram of a drive device for a windowlifter in motor vehicles;

FIG. 2 shows a wiring diagram of a control device in the drive device inFIG. 1;

FIG. 3 shows a block wiring diagram of an evaluating unit in the controldevice according to FIG. 2;

FIG. 4 shows a diagram of the output signals of a sensor for rotationalmovements of the rotor shaft in the drive device according to FIG. 1.

DESCRIPTION OF A PREFERRED EMBODIMENT

The drive device for a window lifter in a motor vehicle shown in theblock wiring diagram in FIG. 1 has an electric d.c. motor 10 which isexcited by a permanent magnet and whose rotor shaft 11 can be driven intwo rotational directions. The rotational movement of the rotor shaft 11indicated at right in FIG. 1 is detected by a sensor 12. The sensor 12is a Hall IC, known per se, which detects the number of revolutions ofthe rotor shaft in conventional window lifting devices, whichinformation is then used for different control measures. It has apermanent magnet 13 which is connected with the rotor shaft 11 so as tobe fixed with respect to rotation relative to it and two Hall elements14, 15 which are arranged so as to be stationary at the rotor shaft 11and are offset by 90° relative to one another. Two output signalscomposed of a sequence of square pulses can be taken off at the twooutput channels 1 and 2 of the Hall IC 12. One pulse periodcharacterizes a revolution of the rotor shaft 11. The pulse frequency isdependent on the rate of rotation of the rotor shaft 11. The two pulsesequences are electrically shifted in phase by 90° relative to oneanother, so that the rotating direction of the rotor shaft 11 can beknown from the direction of the phase shift.

The drive device for the window lifter further has a control device 16connected to a d.c. voltage source 35. The motor 10 is connected to itsoutputs a and b and an output channel 1 or 2 of the Hall IC 12 isconnected to its inputs c and d. One switching contact of a selectionswitch 17 and 18, respectively, which is constructed as a key switch, isconnected with the inputs e and f, respectively, of the control device16. Its other switching contact is connected to an output "+" of thecontrol device 16 carrying positive potential. The selection switch 17is actuated for closing the window and the selection switch 18 isactuated to open the window. An end switch 19 and 20 is connected withthe inputs g, h and i, k, respectively, of the control device 16. Thetwo end switches 19, 20 are normally closed and are opened by the windowlifter in the end positions of the window pane. The end switch 19 isopened in the "window closed" position and the end switch 20 is openedin the "window open" position.

An embodiment example of the control device 16 is shown in FIG. 2 as awiring diagram. In order to switch on the motor 10 in one rotatingdirection or the other two switch-on relays 21, 22 are provided whoserelay windings 23, 24 are connected with the positive pole "+" of thed.c. voltage source 35 via the assigned end switch 19, 20 and theassigned selection switch 17, 18. Every switch-on relay 21, 22 has adouble switching contact comprising switching contacts 25 and 26 or 27and 28. In the closed state the switching contacts 25 and 27 connect theoutputs a and b of the control device 16 with the positive pole "+" ofthe d.c. voltage source 35 and the switching contacts 26 and 28 connectthe outputs b and a with the negative pole "-" of the d.c. voltagesource 35.

For example, if the selection switch 18 actuates "window up" theswitch-on relay 22 will be connected to the positive pole "+" of thed.c. voltage source 35 via the closed end switch 20 for the duration ofthe actuation of the selection switch 18. The two switching contacts 27,28 close and accordingly connect the motor 10 to the d.c. voltage source35 via the outputs b, a of the control device 16. The rotor shaft 11rotates in one rotating direction and the window lifter is driven in the"window open" direction. If the window lifter has reached its endposition in which the window is completely opened, the end switch 20 isopened and the excitement of the switch-on relay 22 is accordinglyswitched off. If the selection switch 17 actuates "window closed", theswitch-on relay 21 is excited and driven via the closed switchingcontacts 25, 26 of the motor 10 in the opposite rotational direction.The window is closed again until the end switch 19 is opened in the endposition.

Since the motor 10 as well as the window lifter are constructed so as tobe extensively free of friction it is possible that the window will beopened unintentionally in the window closing position due to externalinfluences, e.g. strong shaking. To prevent this a rotating movement ofthe rotor shaft 11 resulting during unwanted window movement is detectedby the sensor 12 and a switching on of the motor 10 in a rotatingdirection causing the closing of the window is triggered when adetermined number of revolutions of the rotor shaft 11 has beendetermined. For this purpose the sensor 12 is connected by one of itsoutput channels 1, 2, in this case output channel 1, with the input E ofan evaluating unit 29 whose output A is applied to the relay winding 23of the switch-on relay 21 via the end switch 19. If the evaluating unit29 detects a predetermined number of revolutions of the rotor shaft 11,it produces a switch-on signal which reaches the relay winding 29 viathe output A and causes the closing of the switching contacts 25, 26.

A possible embodiment example of the evaluating unit 29 is shown in theblock wiring diagram in FIG. 3. It has a pulse edge detector 30, a pulseshaper 31, a counter 32 which can be preset, a monostable multivibrator33, and an amplifier 34. The pulse edge detector 30 detects the risingpositive edge of the output signals of the sensor 12 at the input E andsends an output signal to the pulse shaper 31 which generates a countingpulse from it. This counting pulse arrives at the counting input of thecounter 32 which is constructed as a backwards counter and is preset toa predetermined counting step. The counter 32 counts one counting stepbackwards with every counting pulse. After the preset number of countingsteps the counter 32 arrives at the zero level and gives a signal to themonostable multivibrator 33 which jumps to its unstable state for theduration of its resetting time and sends a signal to the outputamplifier 34. The output amplifier 34 applies an exciter current to therelay winding of the switch-on relay 21 for the duration of theresetting time of the monostable multivibrator 33. The relay 21 attractsand the switching contacts 25, 26 close. The motor 10 is switched on andthe rotor shaft 11 rotates in the "window closing" rotating direction.

The end switch 19, which previously closed automatically during theunwanted movement of the window out of the closing position, opens assoon as the closing position of the window is achieved again. Theresetting time of the monostable multivibrator 33 is adjusted in such away that it is greater than the time required for the window to closeagain after switching on the motor 10.

The invention is not limited to the embodiment example described above.Thus, the end switch 19, 20 can be dispensed with and, instead, theoutput signals of the sensor 12 can be made use of for switching off themotor 10 when the two end positions, "window closed" and "window open",are reached. The output signals of the sensor 12 further provide thepossibility of moving automatically to predetermined window positionsand of additionally providing a jamming protection which causes themotor to switch off when there is an obstacle in the movement path ofthe window.

Instead of the window lifter, other movable structural component unitscan also be driven and monitored in both movement end positions forunwanted movement out of the movement end positions. The control device16 then evaluates the sensor signals on both output channels 1, 2 of theHall IC and can accordingly additionally determine the rotatingdirection in which the motor 10 must be driven so that the desiredmovement state of the structural component unit is automaticallyproduced again.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofconstructions differing from the types described above.

While the invention has been illustrated and described as embodied in adrive device for movable structural component units, it is not intendedto be limited to the details shown, since various modifications andstructural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.

What is claimed as new and desired to be protected by Letters Patent isset forth in the appended claims.

I claim:
 1. A drive device for movable structural component unit,particularly in vehicles such as window lifters, sliding-roof actuators,mirror adjusters and the like, the drive device comprising a reversibleelectric motor having a rotor shaft driveable in two rotatingdirections; a control device for switching on said motor in apredetermined rotating direction of said rotor shaft at switch-oncommand; and a sensor assigned to said rotor shaft of said motor fordetecting rotational movements of said rotor shaft, said sensor beingeffective in a switched-off state of said motor, said control devicecontaining an evaluating unit for evaluating signals of said sensor andfor generating said switch-on command in a rotating direction oppositethe rotational movement of said rotor shaft, said sensor providing anoutput signal for a predetermined rotary angle of said rotor shaft, saidevaluating unit being formed so that it generates a counting pulse forevery signal component, counts the counting pulses and generates theswitch-on command at a predetermined number of the counting pulses, saidsensor having a permanent magnet which is fixed with respect to rotationrelative to said rotor shaft, and two stationary Hall sensors which areoffset in the rotating direction of said rotor shaft and supply twopulse sequences composed of square pulses which are phase-shifted to twooutput channels.
 2. A drive device as defined in claim 1, wherein saidtwo stationary Hall sensors are integrated in a Hall IC which suppliessaid two pulse sequences.
 3. A drive device as defined in claim 1,wherein said evaluating unit has an edge detector, a pulse shaper, acounter which can be preset and sends an output pulse when reaching apredetermined counter position so that the switch-on command is derivedfrom the output pulse of said counter.
 4. A derive device as defined inclaim 1, wherein said two stationary Hall sensors are offset by 90° inthe rotating direction of said rotor shaft and supply said two pulsesequences composed of said square pulses which are phase-shifted by 90°.5. A drive device as defined in claim 1, wherein said sensor is formedso that it provides a counting pulse per revolution of said rotor shaft.6. A drive device as defined in claim 1, wherein said sensor is fixedlymounted on said rotor shaft.